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authorMaciej W. Rozycki <macro@orcam.me.uk>2022-04-24 12:47:20 +0100
committerThomas Gleixner <tglx@linutronix.de>2022-05-02 14:29:04 +0200
commit92067440f1311dfa4d77b57a9da6b3706f5da32e (patch)
treef9ffe0b7acd783e727556651645b1d73cf4f9ea9 /kernel/time
parent90be8d6c1f91e1e5121c219726524c91b52bfc20 (diff)
time/sched_clock: Round the frequency reported to nearest rather than down
The frequency reported for clock sources are rounded down, which gives misleading figures, e.g.: I/O ASIC clock frequency 24999480Hz sched_clock: 32 bits at 24MHz, resolution 40ns, wraps every 85901132779ns MIPS counter frequency 59998512Hz sched_clock: 32 bits at 59MHz, resolution 16ns, wraps every 35792281591ns Rounding to nearest is more adequate: I/O ASIC clock frequency 24999664Hz sched_clock: 32 bits at 25MHz, resolution 40ns, wraps every 85900499947ns MIPS counter frequency 59999728Hz sched_clock: 32 bits at 60MHz, resolution 16ns, wraps every 35791556599ns Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <jstultz@google.com> Link: https://lore.kernel.org/r/alpine.DEB.2.21.2204240055590.9383@angie.orcam.me.uk
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/sched_clock.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c
index b1b9b12899f5..ee07f3ac1e5b 100644
--- a/kernel/time/sched_clock.c
+++ b/kernel/time/sched_clock.c
@@ -8,6 +8,7 @@
#include <linux/jiffies.h>
#include <linux/ktime.h>
#include <linux/kernel.h>
+#include <linux/math.h>
#include <linux/moduleparam.h>
#include <linux/sched.h>
#include <linux/sched/clock.h>
@@ -199,11 +200,11 @@ sched_clock_register(u64 (*read)(void), int bits, unsigned long rate)
r = rate;
if (r >= 4000000) {
- r /= 1000000;
+ r = DIV_ROUND_CLOSEST(r, 1000000);
r_unit = 'M';
} else {
if (r >= 1000) {
- r /= 1000;
+ r = DIV_ROUND_CLOSEST(r, 1000);
r_unit = 'k';
} else {
r_unit = ' ';